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Serendipitous Isolation of Non-Vibrio Bacterial Strains Carrying the Cholera Toxin Gene from Environmental Waters in Indonesia
Yusuke Shibata,Ryohei Nomoto,Garry Cores de Vries,Ro Osawa
International Journal of Microbiology , 2013, DOI: 10.1155/2013/406078
Abstract: We initially attempted to isolate a Vibrio cholerae O1 El Tor biotype that carries a novel variant of the cholera toxin gene (ctxAB) from environmental waters of Indonesia, where the seventh cholera pandemic by V. cholerae O1 El Tor biotype began. Nested PCR targeting the gene revealed that a total of eight strains were found to carry ctxAB. However, sequencing of the 16S rRNA genes of these isolates showed they were not V. cholerae but were either Klebsiella, Enterobacter, Pantoea, or Aeromonas. Subsequent nested PCR assays targeting all genes known to be encoded on the CTX phage (i.e., zot, ace, orfU, cep, rstB, rstA, and rstR) showed that one isolate belonged to the Enterobacter genus carried all the genes tested, while the other isolates lacked either 2, 3, or 5 of the genes. This evidence suggests that phages with ctxAB are genetically diverse and can infect not only V. cholerae and V. mimicus but also other species and genera in the form of a pseudolysogen. 1. Introduction Vibrio cholerae is a gastrointestinal pathogen that causes cholera, a notorious enteric disease with serious morbidity and mortality worldwide. The clinical strains belonging to serogroups O1 and O139 are responsible for all the major cholera epidemics and pandemics on record. The main virulence factor causing the disease, cholera toxin (CTX), is encoded by ctxA and ctxB (ctxA and ctxB; collectively referred to as ctxAB) [1]. The ctxAB genes are present on a filamentous phage, called CTX phage, which has been shown to lysogenize only V. cholerae, V. mimicus, and other Vibrio species [2]. To date, the world has experienced seven major pandemics of cholera since the early 19th century. The 5th and 6th pandemics were caused by toxigenic strains belonging to the classical biotype of serogroup O1 that possesses the classical type of ctxB, whereas the ongoing 7th pandemic, which began in 1961 on the island of Sulawesi in Indonesia [1], is caused by the El Tor biotype that carries the El Tor type of ctxB that has an amino acid sequence slightly different from that of the classical type [3]. Over the past two decades, several V. cholerae strains of different serogroups carrying ctxB with amino acid sequences slightly different from each other have emerged. As of 2009, a total of nine genomic variants of ctxB including the classical type have been reported [4]. We therefore attempted to isolate the V. cholerae O1 El Tor biotype that carried the novel ctxB variant gene from environmental waters of Indonesia. During the course of this attempt, we isolated bacterial strains that also
Wide Distribution of O157-Antigen Biosynthesis Gene Clusters in Escherichia coli
Atsushi Iguchi, Hiroki Shirai, Kazuko Seto, Tadasuke Ooka, Yoshitoshi Ogura, Tetsuya Hayashi, Kayo Osawa, Ro Osawa
PLOS ONE , 2011, DOI: 10.1371/journal.pone.0023250
Abstract: Most Escherichia coli O157-serogroup strains are classified as enterohemorrhagic E. coli (EHEC), which is known as an important food-borne pathogen for humans. They usually produce Shiga toxin (Stx) 1 and/or Stx2, and express H7-flagella antigen (or nonmotile). However, O157 strains that do not produce Stxs and express H antigens different from H7 are sometimes isolated from clinical and other sources. Multilocus sequence analysis revealed that these 21 O157:non-H7 strains tested in this study belong to multiple evolutionary lineages different from that of EHEC O157:H7 strains, suggesting a wide distribution of the gene set encoding the O157-antigen biosynthesis in multiple lineages. To gain insight into the gene organization and the sequence similarity of the O157-antigen biosynthesis gene clusters, we conducted genomic comparisons of the chromosomal regions (about 59 kb in each strain) covering the O-antigen gene cluster and its flanking regions between six O157:H7/non-H7 strains. Gene organization of the O157-antigen gene cluster was identical among O157:H7/non-H7 strains, but was divided into two distinct types at the nucleotide sequence level. Interestingly, distribution of the two types did not clearly follow the evolutionary lineages of the strains, suggesting that horizontal gene transfer of both types of O157-antigen gene clusters has occurred independently among E. coli strains. Additionally, detailed sequence comparison revealed that some positions of the repetitive extragenic palindromic (REP) sequences in the regions flanking the O-antigen gene clusters were coincident with possible recombination points. From these results, we conclude that the horizontal transfer of the O157-antigen gene clusters induced the emergence of multiple O157 lineages within E. coli and speculate that REP sequences may involve one of the driving forces for exchange and evolution of O-antigen loci.
Decline of VOC Concentrations with the Aging of Houses in Japan  [PDF]
Motoya Hayashi, Haruki Osawa
Journal of Environmental Protection (JEP) , 2013, DOI: 10.4236/jep.2013.412A1004

The purpose of this investigation is to know the long-term characteristics of VOC concentrations in houses built before the building code in 2003 and to clarify the countermeasures against indoor air pollution in the houses already built. For example, the improvements of living habits, ventilation and the remove of building materials. The concentrations of VOCs were measured in these houses in summer and winter from 2000 to 2005. The results showed that the concentration of formaldehyde decreased in the first year. After that the decline of the concentration was not seen and the concentration changed only with the temperature. The characteristics of decline were thought to be caused by two sorts of emission. One is an emission of concealed formaldehyde in the process of material production and the other is an emission with the generation of formaldehyde from adhesives of urea resin and moisture. The concentration of toluene decreased rapidly in the first year. The concentrations of xylene, ethyl-benzene and styrene showed a similar change. But the concentrations of acetaldehyde which were measured from the summer of 2002 did not decrease and its concentration in some houses was higher than the guideline even in the winter of 2005.

Finite rank intermediate Hankel operators and the big Hankel operator
Tomoko Osawa
International Journal of Mathematics and Mathematical Sciences , 2006, DOI: 10.1155/ijmms/2006/51705
Abstract: Let La2 be a Bergman space. We are interested in an intermediate Hankel operator HφM from La2 to a closed subspace M of L2 which is invariant under the multiplication by the coordinate function z. It is well known that there do not exist any nonzero finite rank big Hankel operators, but we are studying same types in case HφM is close to big Hankel operator. As a result, we give a necessary and sufficient condition about M that there does not exist a finite rank HφM except HφM=0.
Ghrelin and Helicobacter pylori infection
Hiroyuki Osawa
World Journal of Gastroenterology , 2008,
Abstract: Ghrelin is primarily secreted from the stomach and has been implicated in the coordination of eating behavior and weight regulation. Ghrelin also plays an essential role in the mechanism of gastric mucosal defense. Thus, it is important to clarify which diseases primarily influence changes in plasma ghrelin concentrations. Helicobacter pylori (H pylori) infection is involved in the pathogenesis of gastritis, gastric and duodenal ulcer, gastric carcinoma, and mucosa-associated lymphoid tissue lymphoma. H pylori eradication is related to body weight change. Compared, H pylori infected and negative subjects with normal body mass index, plasma ghrelin concentration, gastric ghrelin mRNA, and the number of ghrelin producing cells in gastric mucosa are significantly lower in H pylori infected subjects than in H pylori-negative controls. Plasma ghrelin concentration decreases with the progression of gastric atrophy. Impaired gastric ghrelin production in association with atrophic gastritis induced by H pylori infection accounts for the decrease in plasma ghrelin concentration. However, the ratio of plasma acylated ghrelin to total ghrelin levels is higher in patients with chronic atrophic gastritis than in healthy subjects. This may result from the compensatory increase in plasma active ghrelin concentration in response to gastric atrophy. After H pylori eradication, gastric preproghrelin mRNA expression is increased nearly 4-fold in most cases. However, changes in plasma ghrelin concentrations before and after H pylori cure are not associated with the gastric ghrelin production. Plasma ghrelin changes are inversely correlated with both body weight change and initial plasma ghrelin levels.
Gene Polymorphisms and Chemotherapy in Non-small Cell Lung Cancer
Chinese Journal of Lung Cancer , 2009,
Abstract: The phamacogenetics is being used to predict whether the selected chemotherapy will be really effective and tolerable to the patient. Irinotecan, oxidized by CYP3A4 to produce inactive compounds, is used for treatment of various cancers including advanced non small cell lung cancer (NSCLC) patients. CYP3A4*16B polymorphism was associated with decreased metabolism of irrinotecan. Irinotecan is also metabolized by carboxylesterase to its principal active metabolite, SN-38, which is subsequently glucuronidated by UGT1As to form the inactive compound SN-38G. UGT1A1*28 and UGT1A1*6 polymorphisms were useful for predicting severe toxicity with NSCLC patients treated with irinotecan-based chemotherapy. Platinum-based compounds (cisplatin, carboplatin) are being used in combination with new cytotoxic drugs such as gemcitabine, paclitaxel, docetaxel, or vinorelbine in the treatment of advanced NSCLC. Cisplatin activity is mediated through the formation of cisplatin-DNA adducts. Gene polymorphisms of DNA repair factors are therefore obvious candidates for determinants of repair capacity and chemotherapy efficacy. ERCC1, XRCC1 and XRCC3 gene polymorphisms were a useful marker for predicting better survival in advanced NSCLC patients treated with platinum-based chemotherapy. XPA and XPD polymorphisms significantly increased response to platinum-based chemotherapy. These DNA repair gene polymorphisms were useful as a predictor of clinical outcome to the platinum-based chemotherapy. EGFR kinase inhibitors induce dramatic clinical responses in NSCLC patients with advanced disease. EGFR gene polymorphism in intron 1 contains a polymorphic single sequence dinucleotide repeat (CA-SSR) showed a statistically significant correlation with the gefitinib response and was appeared to be a useful predictive marker of the development of clinical outcome containing skin rashes with gefitinib treatment. The other polymorphisms of EGFR were also associated with increased EGFR promoter activity. EGFR gene mutations and polymorphisms were also associated with EGFR kinase inhibitors response and toxicity.
A Basic Study of the Forecast of Air Transportation Networks Using Different Forecasting Methods  [PDF]
Yuya Takahashi, Rie Osawa, Susumu Shirayama
Journal of Data Analysis and Information Processing (JDAIP) , 2017, DOI: 10.4236/jdaip.2017.52004
Abstract: This research applies network structuring theories to the aviation domain and predicts aviation network growth, considering a flight connection between airports as a link between nodes. Our link prediction approach is based on network structure information, and to improve prediction accuracy, it is necessary to estimate the mechanism of aviation network growth. This research critically evaluates the prediction accuracy of two methods: the receiver operating characteristic curve method (ROC) and the logistic regression method. We propose a four-step method to evaluate the relative predictive accuracy among different link prediction methods. A case study of US aviation networks indicated that the ROC method provided better prediction accuracy compared with the logistic regression method. This result suggests that tuning of the prediction distribution and the regression model coefficients can further improve the accuracy of the logistic regression method.
Finite-rank intermediate Hankel operators on the Bergman space
Takahiko Nakazi,Tomoko Osawa
International Journal of Mathematics and Mathematical Sciences , 2001, DOI: 10.1155/s0161171201001971
Abstract: Let L2=L2(D,r dr dθ/π) be the Lebesgue space on the open unit disc and let La2=L2∩ℋol(D) be the Bergman space. Let P be the orthogonal projection of L2 onto La2 and let Q be the orthogonal projection onto L¯a,02={g∈L2;g¯∈La2,   g(0)=0}. Then I−P≥Q. The big Hankel operator and the small Hankel operator on La2 are defined as: for ϕ in L∞, Hϕbig(f)=(I−P)(ϕf) and Hϕsmall(f)=Q(ϕf)(f∈La2). In this paper, the finite-rank intermediate Hankel operators between Hϕbig and Hϕsmall are studied. We are working on the more general space, that is, the weighted Bergman space.
Cytomegalovirus infection in critically ill patients: a systematic review
Ryosuke Osawa, Nina Singh
Critical Care , 2009, DOI: 10.1186/cc7875
Abstract: Studies in which critically ill immunocompetent adults were monitored for CMV infection in the intensive care unit (ICU) were reviewed.CMV infection occurs in 0 to 36% of critically ill patients, mostly between 4 and 12 days after ICU admission. Potential risk factors for CMV infection include sepsis, requirement of mechanical ventilation, and transfusions. Prolonged mechanical ventilation (21 to 39 days vs. 13 to 24 days) and duration of ICU stay (33 to 69 days vs. 22 to 48 days) correlated significantly with a higher risk of CMV infection. Mortality rates in patients with CMV infection were higher in some but not all studies. Whether CMV produces febrile syndrome or end-organ disease directly in these patients is not known.CMV infection frequently occurs in critically ill immunocompetent patients and may be associated with poor outcomes. Further studies are warranted to identify subsets of patients who are likely to develop CMV infection and to determine the impact of antiviral agents on clinically meaningful outcomes in these patients.Cytomegalovirus (CMV) is a major β herpes virus and a significant human pathogen. Infection is common with seroprevalence rates increasing steadily from 65% among 40 to 49 year olds to 91% in those aged 80 years or over [1]. After primary infection, CMV, like other β herpes viruses, establishes life-long latency. In immunocompetent individuals, asymptomatic viral shedding may be detectable in saliva or urine; however, cell-mediated host immune responses prevent the development of overt CMV disease.In contrast, CMV infection has been shown to lead to significant disease in immunocompromised hosts such as those with HIV infection or transplant recipients. End-stage HIV-infected patients with a CD4 lymphocyte count of less than 50 cells/mm3 are at the highest risk of developing CMV retinitis [2]. In transplant recipients, CMV disease occurs in 11 to 72% of patients especially in the first three months after transplant while the patient
Trabalho "porco, perigoso e pesado" dos dekasseguis e incidência de doen as psíquicas
Cibele Cristina Osawa
Physis: Revista de Saúde Coletiva , 2006, DOI: 10.1590/s0103-73312006000100010
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